Differentiation of severe coronary artery calcification in the Multi-Ethnic Study of Atherosclerosis

Background: Coronary artery calcium (CAC) scores predict coronary heart disease (CHD) risk. Little is known, however, about the distinctive risk among asymptomatic individuals with very high CAC (≥1000) compared to high CAC (400-999). Methods and results: We compared CHD risk factors and event rates between participants with very high CAC (n= 257) and high CAC (n= 420) among adults free of clinical CHD in the Multi-Ethnic Study of Atherosclerosis (MESA). CAC was measured at baseline, and participants were followed for a median of 68 months. Very high CAC (≥1000), compared to high CAC (400-999), was associated with male gender (OR 3.10, p< 0.001) and older age (OR 1.42 per 10 year increase, p< 0.001). Chronic kidney disease (CKD) was associated with very high CAC (OR 1.66, p= 0.009) with a greater prevalence of moderate CKD (GFR 30-59) in the ≥1000 group (25% vs. 18%). Those with very high CAC were more likely to develop angina (adjusted HR 1.72 [95% CI 1.03-2.90], p= 0.04), but not more likely to experience myocardial infarction, resuscitated cardiac arrest, or CHD death (adjusted HR 1.17, [95% CI 0.64-2.12] p= 0.61) compared to high CAC. Total CHD event rates were greater for very high CAC (3.7 per 100 person-years) compared to high CAC (2.6 per 100 person-years). Conclusions: Both high and very high CAC are associated with an elevated risk of CHD events in those without symptomatic CHD at baseline; however, very high CAC is associated with an increased risk of angina, but not CHD death or MI, compared to high CAC.